Re: [gentoo-user] emerge sets syntax (@world vs. world)

[Alan McKinnon]

On Wed, 12 Dec 2012 12:53:01 +0100
Francesco Turco <fturco@××××××××.fm> wrote:

> Hello.
>
> A couple of weeks ago I filed a bug because in the Installation
> Handbook I found some references of the "world" set in emerge
> commands, as opposed to "@world":
> https://bugs.gentoo.org/show_bug.cgi?id=445184
>
> The bug was closed as invalid, and I was told that:
>
> > sets with the @ prefix are a portage-2.2 feature, which is still
> > hardmasked and thus not documented.
>
> The fact is that I have portage-2.1.11.37, not 2.2, and man emerge
> says:
>
> > When used  as  arguments to emerge sets have to be prefixed with @
> > to be recognized.
>
> One possibility is that documentation stick with the stable portage
> package, not the testing one (I have a ~amd64 system only). But I
> checked portage 2.1.11.31 (the latest stable amd64 portage package
> version) and the previous phrase is there, too.
>
> I know it's not a very important issue, but I'd still like to know if
> I'm wrong or not, and why.

You are wrong, the docs and the man pages are correct.

The problem is that the word "set" is used in two different ways, one
loosely and the other with reference to an exact construct.

portage-2.2 introduced the concept of "a defined set" under user
control. It's a list of packages that portage treats as a whole chunk
of things together and the user can define what he wants in a set and
give it a name. When used with emerge, sets like this must have an "@"
prefix so portage can tell them apart from regular packages. Portage
also dynamically creates sets internally that work the same way, things
like @world and @system and @preserved-rebuild. You can use these too,
you just can't define them or modify them directly.

The portage man page has unfortunately also used the word "set" for a
different reason. Portage has always had a concept of "world" (not
@world) and "system" (not @system) which were really "just a bunch of
stuff that happens to pop out of portage because it's hard-coded that
way". And the docs say things like 

emerge world

and call the "world" part "the world set".

"Set" here is a homonym - two completely different words with different
meanings that just happen to be spelled and sound the same. 

English too has the identical problem - the word "set" holds the
undisputed record for the English word with the most definitions - it
had 134 last time I checked. That's right, 134 meanings for 3 letters
as verified by that big Oxford dictionary that you need a wheel barrow
to carry it around in (and a big magnifying glass to read). It's not
surprising some of that leaked into Portage :-)

The docs you mention are using the second, loose, definition of the
word.
I recommend you treat it as simply a problem of over-loaded human
languages and just deal with it

:-)

-- 
Alan McKinnon
alan.mckinnon@×××××.com